Gains and losses in intertemporal preferences: a behavioural study

According to recent evidence (Frederick, Loewenstein, & O’Donoghue, 2002), the traditional Discounted Utility model (Samuelson, 1937) has a limited ability to describe realistic models of behaviour and indeed there are several documented empirical regularities that seem to contradict this statement both in certainty and uncertainty conditions. This study focused on one of the best documented anomalies: sign effect or gain-loss asymmetry (Frederick et al., 2002; Loewenstein & Prelec, 1992; Read, 2004). Specifically, the study investigated the intertemporal preference for symmetric monetary rewards and punishments in certain conditions, and the no wealth effects hypothesis (Dimitri, 2007) by asking subjects to choose between two positive or two negative euro amounts available at different points in time. The experimental design applied here followed the same behavioural pattern of the neuroeconomics’ study on monetary rewards realized by McClure et al. (2004). The results confirmed a gain-loss asymmetry at least for medium and large euro amount and suggested new directions of research.intertemporal preferences; gains; losses; certainty; sign effect .

Time estimation in mild Alzheimer's disease patients

<p>Abstract</p> <p>Background</p> <p>Time information processing relies on memory, which greatly supports the operations of hypothetical internal timekeepers. Scalar Expectancy Theory (SET) postulates the existence of a memory component that is functionally separated from an internal clock and other processing stages. SET has devised several experimental procedures to map these cognitive stages onto cerebral regions and neurotransmitter systems. One of these, the time bisection procedure, has provided support for a dissociation between the clock stage, controlled by dopaminergic systems, and the memory stage, mainly supported by cholinergic neuronal networks. This study aimed at linking the specific memory processes predicted by SET to brain mechanisms, by submitting time bisection tasks to patients with probable Alzheimer's disease (AD), that are known to present substantial degeneration of the fronto-temporal regions underpinning memory.</p> <p>Methods</p> <p>Twelve mild AD patients were required to make temporal judgments about intervals either ranging from 100 to 600 ms (short time bisection task) or from 1000 to 3000 ms (long time bisection task). Their performance was compared with that of a group of aged-matched control participants and a group of young control subjects.</p> <p>Results</p> <p>Long time bisection scores of AD patients were not significantly different from those of the two control groups. In contrast, AD patients showed increased variability (as indexed by increased <it>WR </it>values) in timing millisecond durations and a generalized inconsistency of responses over the same interval in both the short and long bisection tasks. A similar, though milder, decreased millisecond interval sensitivity was found for elderly subjects.</p> <p>Conclusion</p> <p>The present results, that are consistent with those of previous timing studies in AD, are interpreted within the SET framework as not selectively dependent on working or reference memory disruptions but as possibly due to distortions in different components of the internal clock model. Moreover, the similarity between the timing patterns of elderly and AD participants raises the important issue of whether AD may be considered as part of the normal aging process, rather than a proper disease.</p

The place of Free Will: the freedom of the prisoner

Debates about the concept of Free Will date back to ancient times. About 40 years ago Benjamin Libet designed an experiment showing that the conscious intention to move is preceded by a specific pattern of brain activation. His finding suggested that unconscious processes determine our decisions. Libet-style experiments have continued to dominate the debate about Free-Will, pushing some authors to argue that the existence of Free Will is a mere illusion. We believe that this dispute is because we often measure free will using arbitrary human decisions rather than deliberate actions. After reviewing the definition of free will and the related literature we conclude that the scientific evidence does not disprove the existence of Free Will. However, our will encounters several constraints and limitations that should be considered when evaluating our deeds’ personal responsibility

Sensory Loss Mimicking Cauda Equina Syndrome due to Cervical Spinal Lesion in a Patient with Clinically Isolated Syndrome

We describe the case of a 39-year-old woman with signs and symptoms suggesting cauda equina syndrome. Lumbosacral magnetic resonance imaging (MRI) demonstrated no lesion at this level, while cervical MRI showed a T2-hyperintense lesion in the middle-right anterolateral region of the cervical spinal cord, which may explain the symptoms by involving the anterior spinothalamic tract. We suggest that in cases with cauda equina syndrome presentation and normal lumbosacral MRI, a cervicodorsal lesion should be considered during diagnostic assessment

Gains and losses in intertemporal preferences: a behavioural study

The aim of this study was to investigate individual behavior in choosing symmetric monetary gains and losses under certainty. As in previous research, results showed that gains and losses are not equal and seem to be drawn by different internal principles of choice. Subjects preferred to lose sooner in time against average or high losses. Furthermore, considering the proportional difference between short and long-term alternatives of choice, the percentage of responses for early outcomes was increasing for losses and decreasing for gains

Eight Weddings and Six Funerals: An fMRI Study on Autobiographical Memories

“Autobiographical memory” (AM) refers to remote memories from one's own life. Previous neuroimaging studies have highlighted that voluntary retrieval processes from AM involve different forms of memory and cognitive functions. Thus, a complex and widespread brain functional network has been found to support AM. The present functional magnetic resonance imaging (fMRI) study used a multivariate approach to determine whether neural activity within the AM circuit would recognize memories of real autobiographical events, and to evaluate individual differences in the recruitment of this network. Fourteen right-handed females took part in the study. During scanning, subjects were presented with sentences representing a detail of a highly emotional real event (positive or negative) and were asked to indicate whether the sentence described something that had or had not really happened to them. Group analysis showed a set of cortical areas able to discriminate the truthfulness of the recalled events: medial prefrontal cortex, posterior cingulate/retrosplenial cortex, precuneus, bilateral angular, superior frontal gyri, and early visual cortical areas. Single-subject results showed that the decoding occurred at different time points. No differences were found between recalling a positive or a negative event. Our results show that the entire AM network is engaged in monitoring the veracity of AMs. This process is not affected by the emotional valence of the experience but rather by individual differences in cognitive strategies used to retrieve AMs

Cerebrospinal fluid anti-Epstein-Barr virus specific oligoclonal IgM and IgG bands in patients with clinically isolated and Guillain-Barré syndrome

Epstein-Barr virus (EBV) has been implicated in multiple sclerosis (MS) pathogenesis. We aimed to assess the frequency of EBV-specific IgG and IgM oligoclonal bands (OCB) in cerebrospinal fluid (CSF) of 50 patients with clinically isolated syndrome (CIS) and in 27 controls with Guillain-Barré syndrome (GBS). Furthermore, we assessed correlations between the presence of OCB and CIS patients' CSF, MRI, and clinical variables. There was no difference in the proportion of CIS and GB patients with positivity for anti-EBV-specific IgG/IgM OCB. There were no correlations between OCB and analyzed variables, nor were they predictive of a higher disability at 3&nbsp;years

Role of cerebrospinal fluid biomarkers to predict conversion to dementia in patients with mild cognitive impairment: a clinical cohort study

Abstract Background: Cerebrospinal fluid (CSF) levels assessment of Aβ1-42 and Tau proteins may be accurate diagnostic biomarkers for the differentiation of preclinical Alzheimer's disease (AD) from age-associated memory impairment, depression and other forms of dementia in patients with mild cognitive impairment (MCI). The aim of our study was to explore the utility of CSF biomarkers in combination with common cognitive markers as predictors for the risk of AD development, and other forms of dementia, and the time to conversion in community patients with MCI. Methods: A group of 71 MCI patients underwent neurological assessment, extended neuropsychological evaluation, routine blood tests, ApoE determination, and lumbar puncture to dose t-tau, p-tau181, Aβ1-42. We investigated baseline CSF and neuropsychological biomarker patterns according to groups stratified with later diagnoses of AD conversion (MCI-AD), other dementia (MCI-NAD) conversion, or clinical stability (sMCI). Results: Baseline Aβ1-42 CSF levels were significantly lower in MCI-AD patients compared to both sMCI and MCI-NAD. Additionally, p-tau181 was higher in the MCI-AD group compared to sMCI. The MCI-AD subgroup analysis confirmed the role of Aβ1-42 in its predictive role of time to conversion: rapid converters had lower Aβ1-42 levels compared to slow converters. Logistic regression and survival analysis further supported the key predictive role of baseline Aβ1-42 for incipient AD and dementia-free survival. Conclusions: Our results confirm the key role of CSF biomarkers in predicting patient conversion from MCI to dementia. The study suggests that CSF biomarkers may also be reliable in a real world clinical setting

An EEG-fMRI Study on the Termination of Generalized Spike-And-Wave Discharges in Absence Epilepsy

INTRODUCTION: Different studies have investigated by means of EEG-fMRI coregistration the brain networks related to generalized spike-and-wave discharges (GSWD) in patients with idiopathic generalized epilepsy (IGE). These studies revealed a widespread GSWD-related neural network that involves the thalamus and regions of the default mode network. In this study we investigated which brain regions are critically involved in the termination of absence seizures (AS) in a group of IGE patients. METHODS: Eighteen patients (6 male; mean age 25 years) with AS were included in the EEG-fMRI study. Functional data were acquired at 3T with continuous simultaneous video-EEG recording. Event-related analysis was performed with SPM8 software, using the following regressors: (1) GSWD onset and duration; (2) GSWD offset. Data were analyzed at single-subject and at group level with a second level random effect analysis. RESULTS: A mean of 17 events for patient was recorded (mean duration of 4.2 sec). Group-level analysis related to GSWD onset respect to rest confirmed previous findings revealing thalamic activation and a precuneus/posterior cingulate deactivation. At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset). The contrast GSWD offset versus onset showed a BOLD signal increase over the precuneus-posterior cingulate region bilaterally. Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects. CONCLUSION: The role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS. The increased BOLD signal at precuneal/posterior cingulate cortex might reflect the recovery of neural activity in regions that are "suspended" during spike and waves activity, as previously hypothesized